Vascular aneurysms, which result from abnormal dilation of a blood vessel, can occur in any blood vessel. For instance, vascular aneurysms can occur in the aorta and peripheral arteries. The majority of aortic aneurysms occur in the abdominal aorta below the renal arteries. Often the abdominal aortic aneurysm extends into areas of bifurcation (e.g., the inferior end of the aorta where it bifurcates into the iliac arteries) or segments of the aorta from which other branch arteries extend.
Techniques have been developed for repairing abdominal aortic aneurysms by intraluminally delivering an endovascular graft to the aneurysm site through the use of a catheter-based delivery system. The endovascular grafts typically comprise a tube of pliable material (e.g., expanded polytetrafluoroethylene (ePTFE) or woven polyester) in combination with a graft anchoring component, which operates to hold the tubular graft in its intended position within the aorta. Most commonly, the graft anchoring component is formed of a stent or frame that is radially expandable to exert outwardly directing radial pressure against the surrounding blood vessel wall. The stent or frame can be either attached to or incorporated into the body of the tubular graft or provided separate from the graft and deployed within the graft.
Unfortunately, not all patients diagnosed with abdominal aortic aneurysms are considered to be candidates for endovascular grafting. Most endovascular grafts, which have been designed for treating abdominal aortic aneurysms, require the patient being treated have a proximal aortic neck inferior the renal arteries of at least 1 cm in length and a distal iliac neck less than 2.0 cm in diameter.
Additionally, the deployment of endovascular grafts within regions of the aorta from which the renal, superior mesenteric, celiac, intercostal, and/or subclavian arteries extend present additional technical challenges because, in those cases, it is advantageous to design, implant, and maintain, the endovascular graft in a manner which does not impair the flow of blood into these arteries.